A polarimeter is an optical instrument used in the transmissive mode for determining the polarization state of a light beam,
or the polarization-altering properties of a sample, such as diattenuation, retardation and depolarizion.1 (Reflective
"polarimeters" are typically called ellipsometers.) Polarimeters can, thus, be broadly categorized as either light-measuring
polarimeters or sample-measuring polarimeters. A light-measuring polarimeter is also known as a Stokes polarimeter,
which measures the polarization state of a light beam as described by the Stokes parameters. A sample-measuring
polarimeter is also known as a Mueller polarimeter, which measures the complete set or a subset of polarization-altering
properties of a sample.
Polarimeters can also be categorized by whether they measure the complete set of polarization properties. If a Stokes
polarimeter measures all four Stokes parameters, it is called a complete Stokes polarimeter; otherwise, an incomplete or a
special Stokes polarimeter. Similarly, there are complete and incomplete Mueller polarimeters. Nearly all samplemeasuring
polarimeters are incomplete or special polarimeters, particularly for industrial applications. These special
polarimeters bear different names. For example, a circular dichroism spectrometer, which measures the differential
absorption between left and right circularly polarized light (&utri;;A= AL - AR), is a special polarimeter for measuring the
circular diattenuation of a sample; a linear birefringence measurement system is a special polarimeter for measuring the
linear retardation of a sample.
Polarimeters have a broad range of applications in both academic research and industrial metrology. Polarimeters are
applied to chemistry, biology, physics, astronomy, material science and many other scientific areas. Polarimeters are used
as metrology tools in the semiconductor, fiber telecommunication, flat panel display, pharmaceutical and many other
industries. Different branches of polarimetry have established their own scientific communities, within which regular
conferences are held.2-6 Tens of thousands of articles have been published on polarimeters and their applications, including
books and many review articles.1, 7-15 In this paper, I will focus on polarimeters using the photoelastic modulator (PEM).16-18

Photomechanics, one kind of interferometry based experimental methods used to measure the mechanical quantities, can
provide interferometric fringes using specially designed optical setups. Analysis of mechanical quantities from the
interferometric fringes needs good understanding of their distribution, which is often not easy when analyzing a
complicated model. At this time, the simulation of the experimental results on similar models will greatly improve the
experimental data processing of photomechanics. Moreover this simulation will also greatly contribute to the teaching of
photomechanics. In this paper, a basic framework for photomechanics simulation is firstly proposed. The specific
algorithms for simulation of the two important photomechanics methods, photoelasticity and electronic speckle pattern
interferometry (ESPI), are developed. A photomechanics simulation system containing photoelasticity and ESPI is
constructed. When simulation, the distribution of the mechanical quantities is firstly calculated using finite element
method (FEM), and then the interferometric fringes are generated through the virtual realization of the interferometric
procedure in the corresponding optical setup. The whole simulation procedure is realized with the Matlab software.
Comparison between the results from simulation and the real experiment shows the validity of the simulation algorithms.

In this paper, we have developed a spectroscopic topological Stokes polarimeter using an axisymmetrical quarter wave
plate (AQWP). The AQWP is fabricated by the alignment of segments of quarter wave films. The azimuthal angles of
the polarization element are changed in according with its own segment. This element works as same the technique as
the rotating quarter wave plate. In the experiment, we evaluated birefringence distribution of the AQWP. By changing a
position of polarized singularity point in the beam spot, we can measure states of polarization. We demonstrate that the
change of polarization states is corresponded with the change of the polarized singularity points.

In this paper, an approach based on the objective speckles field to measure the elastic modulus of solid material with
three-points bending method is presented. The speckle images of the loading force rod under different loading are
recorded and performed Fast Fourier Transformation (FFT), the deflection of the specimen can be obtained. The Young's
modulus of the specimen calculated agrees well with that of stretch approach. The approach presented in this paper has
advantage of simplicity, noncontact and high accuracy.

Besides the requirement on high contrast and low noise, the more important aspect to affect the accuracy of the optical
extensometer is the pixel resolution of the digital image. The resolution of the marker positioning algorithms is often
evaluated as pixel, and the higher pixel resolution will induce a higher strain measurement resolution in optical
extensometer. Since the algorithm error is always seen as a constant, the strain error is decreased with the distance of the
measured region increases when using optical extensometer. On the other hand, the lens distortion will affect the
accuracy of the marker positioning algorithms. If the distance of the measured region increases, the lens distortion error
will also increase for that the lens distortion is much evident at the image margin. Therefore, when applying optical
extensometer, a balance should be found between the algorithm error and the high distortion of the marker image. In
order to obtain the best measurement accuracy, the marker positions for optical extensometer should be optimized. An
optimization model for choosing best marker position for optical extensometer is constructed on the considering of the
pixel resolution and second order lens distortion. It can be concluded that the extensometer using markers located at the
position optimized from the optimization model would give the best measurement results, and the law that the best
distance between the two markers will change with the size of the strain if the distortion parameters of the camera is
given has been found.

This paper focuses on the effect of operating temperature of uncooled CCD on the strain measurement error when the
CCD is used to measure strain in an optical extensometer. A special experiment is designed in which an optical
extensometer is used to measure the strain and a thermocouple is used to measure the temperature of CCD. The results
show that the measured temperature of CCD has a similar tendency with the change of the measured strain. For different
types of uncooled CCD, the temperature varies about 5~10 degree from the beginning of the experiment to the end, and
the error of the measured strain induced by the temperature was about 120~180με. It is considered that the error is related
to the inherent noise of the electronic components of the CCD whose operating mode is sensitive to the temperature
change. When using the optical extensometer, it is suggested to preheat the CCD 1~2 hours before the experiment
especially in doing high accuracy measurement. Otherwise, the strain induced by the operating temperature should be
eliminated from the measurement results through conducting temperature compensation method mentioned in this paper.

In general, eddy current sensors are point-based sensors with a very high sensitivity but are very slow because of
scanning. Optical visual inspections can be very fast but have difficulty in detection of tiny flaws. Magneto-optical
imaging is a hybrid sensing technique that combines the advantages of both the eddy current sensor and the optical
visual inspection. It has a very high sensitivity and fast inspection speed up to 100mm per second. This paper discusses
the optical system design in a magneto-optical imaging sensor including wavelength selection analysis, image contrast
enhancement option, and frame subtraction, etc. Theoretical analysis is given as well as initial testing results.

Inner profile measurement is an important matter in such fields as medicine, dentistry and anthropology as well as
mechanical engineering and other industrial applications. Here we describe recent development of our measurement
principle for inner diameter of pipes and/or holes. The key device in this technique is a ring beam device which
consists of a conical mirror and a laser diode. And the fundamental principle is based on optical sectioning without
using any contact type stylus. The optically sectioned profile of an inner wall of a pipe-like object is analyzed to give
the inner profile in addition to the inner diameter. This optical instrument with a simple and small configuration is
now under development for practical uses. In our hitherto trial experimental works, the availability of this instrument
has been evaluated in many cases and availability for practical applications is expected, especially, for measurement
and inspection of mechanical components and elements besides pipes. This ring beam device consisting of a conical
mirror and a LD is assembled to form a disk-like light sheet. We show measurement result of pipes and holes, and, at
the same time, report a compact inner profile measuring instrument at this point. Both the ring beam device and a
miniaturized CCD camera are fabricated into a glass tube. Availability of this instrument is shown by measuring the
inner profiles of various pipes. In response to this trial, there appeared a strong request that not only the internal but
external profiles should be measured simultaneously. Therefore we propose potentially possible method for
measurement of external profile at the same time with internal profile. If one pair of concave mirrors are used in our
arrangement, external profile is captured. In combination with inner profile measurement technique, simultaneous
measurement of inner and outer profiles becomes attainable. A measurement result on a bevel gear shows availability
of here proposed principle. In addition, we are trying to extend our technique to check defects and/or flaws on the
inner wall of pipe-like objects.

To improve difficulties inherent to the conventional three-dimensional profiling system based on pattern projection
method, we have proposed incorporating a recent digital device such as a MEMS scanner into projection optics. Due to
this revision, first of all, such a small size system as a palm-top camera is attainable, and low cost measurement system is
potentially realized. In this system, we can control the scanner to produce the projection pattern with appropriate
periodical structure and sinusoidal intensity distribution. Due to this flexible pattern projection, phase-shifting technique
becomes applicable for industrial inspection and measurement in automobile industry and others. The camera is as small
as a photographic digital camera in dimensional size. In addition, our recent improvement of measuring performance by
modulating the projected pattern is to be demonstrated.

Phase shifting based measurements have been well established for use in both interferometry and structured light based
measurements. The use of modern LCD, DLP or LCOS based projectors to create and shift projected patterns for use in
phase shifting systems has provided new capabilities such as pattern masking, adjustable resolutions and active
preprocessing, along with many challenges. Now the latest consumer projection technology has made available low
cost, pocket-sized projectors, some with built in memory. These small projectors open up the possibility of mini-phase
shift systems, as well as the possibility of portable measurement systems. This paper explores some of the possibilities
for systems made with pocket size pattern projectors, and what some of the limitations may be that will need to be
overcome. Experimental data will be presented that illustrates some of these challenges.

This paper describes progressive generations of hand held triangulation sensors for measuring small features, from edge
breaks to corrosion pits. We describe the design considerations, ergonomics, packaging and interface between the device
and part, such as the sensor tip and optional fixtures. We then present a customized design to address different types of
surface features and defects. Next, we present the calibration concept, and its execution. The paper closes by
summarizing system performance evaluation experiments and their results. It was shown that the system is capable of
measuring edges down to a radius of 250 microns at a repeatability of 50 microns.

A simple optical system for small rotation angle measurement is constructed in this paper. A laser diode is fixed on the
rotation part of the mechanism and the laser beam is received by a screen. The position of the spot could be registered
from the image captured by CCD camera using the gray centroid algorithm. Then rotation could be obtained from the
spot movement according to geometrical relationship. In order to verify the system and evaluate its accuracy, a
deflection test of a low carbon steel cantilever beam is performed. It shows that the maximum relative error of
experiment results and theoretical value is less than 1.5%, the measuring accuracy and stability is satisfied. The system
in this paper has many advantages, such as high resolution, low cost, great convenience and could be used to measure
small rotation angles of very complex mechanisms under non-contact request.

A competitive homemade two-coordinate autocollimator is presented, which is able to measure the angle along the
horizontal and vertical axis by using a single linear CCD to detect the three image point positions of the N shape
reticle on the CCD, with total measurement error no greater than 5urad in the measurement range of ±2100urad
and the dynamic response frequency 2KHz.

This paper presents an absolute phase calculation method from one composite RGB fringe pattern image by using
the windowed Fourier transform (WFT) algorithm and the optimum three-frequency selection method. Three fringe
patterns having the optimum fringe numbers are coded into the red, green and blue channels of a composite color
image. The generated composite RGB image is projected onto a measured object surface from a Digital Light
Processing (DLP) projector and the deformed fringe patterns captured by a color CCD camera from a different
viewpoint. The wrapped phase information will be calculated by the WFT algorithm. The WFT algorithm limits the
processed image to a small area, so it can give much better phase near edges or discontinuities than FT algorithm.
Applying the WFT algorithm to the three fringe patterns obtains three wrapped phase maps. An absolute phase map
is calculated pixel by pixel from one composite RGB fringe pattern image after applying the optimum threefrequency
selection method to the three obtained wrapped phase maps. Therefore, the proposed method can
measure absolute phase of objects having discontinuous surfaces from one snapshot image. Experimental results on
moving discontinuous objects show that the proposed method reliably obtains the absolute phase information.

A high-resolution, dynamic Three-dimensional (3-D) profilometry based on the combined stereovision and color-encoded digital
fringe projection is proposed. In this technique, a sinusoidal fringe pattern is encoded with spatial neighborhood strategy based on De
Bruijn sequences. A decoding algorithm for the color pattern is presented. The absolute phase value is retrieved by space method
based on locally intensity variety, and unwrapped by dividing the periods based on the intensity peak and the corresponding color
information. Therefore, only a single color image is needed to realize the unique code in pixel dimension, which meets the demand of
high-resolution, real-time 3D shape measurement. That means this technique could realize pixel-level resolution and measure
disconnected objects. Since the phase value at each pixel is only used to assist stereo matching, the 3-D reconstruction could be realtime,
and the accuracy is also enhanced. A measurement system consisted of one projector and two cameras is developed.
Experimental results are presented to show the feasibility of the proposed method.

A profilometry based on Fizeau interferometer using the optical comb and the sinusoidal phase modulation technique
is demonstrated. The optical comb generated with the Fabry-Perot etalon and a SLD is introduced in the Fizeau
interferometer. The interval wave number of comb is swept by controlling the resonance length of the Fabry-Perot
etalon. The sweeping range is about 500 μm. The displacement measurement is performed by determination of zerophase
or π-phase positions. The accuracy estimated from 5 repeated experiments is about 0.2 rad.

Displacement information of a moving target can be detected using an optical feedback self-mixing interferometry
(OFSMI) system. A sensing signal observed from the OFSMI system is called self-mixing signal (SMS). The paper
studies the waveform features of the SMSs and proposes an algorithm for reconstructing the displacement of a moving
target. The reconstruction accuracy of the algorithm mainly depends on the locating accuracy for those characteristic
points on a SMS. A set of rules for identifying those characteristic points are described in the paper. The proposed
algorithm is verified by simulation signals firstly, and then applied on extensive SMSs which are obtained from the
experimental set-up. The results show that the displacement of the external moving target can be reconstructed under
different feedback levels.

Optical feedback Self-mixing Interferometry (OFSMI) can achieve a high-resolution displacement sensing and
measurement by using advanced digital signal processing. However, most existing signal processing algorithms used for
OFSMI signals are implemented on a PC by Matlab or other programming languages. In this case, the whole structure of
OFSMI sensing system is incompact and the measurement is in low speed. The design trends in sensing systems are
towarding to small size, high integration and fast real time processing. These trends require us to improve the existing
OFSMI design. It is a good solution to apply Field-programmable gate arrays (FPGAs) technique onto OFSMI sensing
systems. In this work, we designed a FPGA based signal processing unit for an OFSMI displacement sensing system.
The OFSMI sensing signals observed from an OFSMI system is connected to a FPGA development board (Spartan-3E)
for high speed signal processing. The FPGA processing unit retrieves the displacement information carried in the OFSMI
signals. The FPGA design includes noise reduction, signal peak detection and impulse magnitude tracking. As the
magnitude of the sensing signal is time-varying, for adapting the variation, a dynamic updating algorithm is introduced
in the magnitude tracking unit. Both simulation and hardware co-simulation show that the OFSMI system with a FPGA
based signal processing unit can achieve fast and reliable displacement sensing.

We propose a measurement method of vibrational surface profile for an ultrasonic motor (USM) using a stroboscopic
oblique incidence interferometer. A time-dependent behaviors of the stator, one of the main components
of the USM, is of considerable practical interest for development of new devices. owever it is difficult to observe
its surface profile because there are diffused and vibrational surface. An obliquely incident light would offer
advantage of the diffused surface because of higher reflectance. Furthermore, for detecting interferences at the
vibrational surface profile, a modulated light source is synchronized with electrical signals of the USM. We are
successful to detect a vibrational surface of the stator.

Birefringent dual-frequency laser based on frequency splitting technology has been employed to obtain the frequency
difference from approximate 40 MHz to several hundreds MHz. In this paper, the mechanism of frequency splitting in
birefringent dual-frequency laser with intracavity quartz crystal is analyzed. Beside the birefringence effect, the optical
activity of quartz crystal and the self-reproduction of laser are considered. The formulae of the polarization angles and
the frequency difference of the two lasing eigen-modes are deduced in detail, and the continuities of their curves are
discussed. Based on these formulae, the theoretical curves of polarization angle and frequency difference are calculated,
which are consistent well with their experimental curves.

recently successfully introduced into optics. Optical FMCW interference naturally generates a dynamic signal, both the
phase and frequency of which are relative to the optical path difference between the two interfering optical waves.
Hence, optical FMCW interference not only can measure the relative change of optical path difference (or other related
parameters) more accurately and easily, but also can measure the absolute value of optical path difference (or other
related parameters). The phase measurement gives a resolution thousands of times higher than the frequency
measurement. Particularly, since the signal of optical FMCW interference is a dynamic signal, to calibrate the fractional
phase, distinguish the phase-shift direction and count the number of full periods is quite easy. Therefore, compared with
traditional optical homodyne interference, optical FMCW interference can offer a higher accuracy and a longer
measurement range. During the last few years, some important achievements in both the theory and application of optical
FMCW interference have been made. Today, optical FMCW interference has become a well-defined new branch of
physical optics. The investigation of optical FMCW interference not only extends our knowledge about the nature of
light, but also offers a new advanced technology for optical metrology. Optical FMCW interference can be used to
upgrade some existing optical instruments and to create the new-conceptual optical instruments. In this paper, I attempt
to review the principle and applications of optical FMCW interference in metrology.

The multi-wavelength back-propagation (MWB) method enables to determine precisely the optical path
different (OPD) longer than the optical wavelength from detecting the amplitude and phase of the
interference signal for the multiple wavelengths. In this study, we demonstrate a 1-dimensional thickness
profile measurement by the MWB and sinusoidal phase modulation (SPM) technique with a spectral
interferometer. The OPD for the front and rear reflecting surfaces of a glass film with the thickness of 100
μm are measured. The thickness profile is successfully measured with repeatability of 2 nm estimated
from a standard error between 9 repeatedly-measured profiles.

Two light beams reflected from a front and rear surfaces of a glass film of 20 micron thickness interfere with
each other in a common path interferometer. Sinusoidal wavelength-scanning light with the scanning amplitude
of 5 nm and frequency of 15 KHz is used to generate a sinusoidal phase-modulated interference signal with the
modulation amplitude of 2.6 rad. The phase of the interference signal provides the thickness variation of the film,
whose measurement accuracy is a few nanometers. Moreover, in order to achieve a high spatial resolution and a
wide measurement region a focused beam is scanned on the surface of the film with a rotating mirror.

This paper analyzes the phase error for a 3-D shape measurement system that utilizes our recently proposed projector defocusing
technique. In this technique, by defocusing binary structured patterns, seemingly sinusoidal ones can be generated,
and 3-D shape measurement can be performed by fringe analysis. However, there are still significant errors if the object
is not within a certain depth range where the defocused fringe patterns still have binary structures. In this research, we
experimentally studied a large depth range of defocused fringe patterns, from close to be binary to to be sinusoidal, and its
associated phase errors are analyzed. We established a mathematical phase error function in terms of the wrapped phase
and the depth z. Finally, the mathematical function is calibrated and is used to compensate for the phase error at arbitrary
depth ranges within the calibration volume. Experiment will be presented to demonstrate the success of this proposed
technique.

We present a simple calibration method of the phase-based 3D imaging systems based on an uneven fringe
projection method. The relationship between absolute phase and depth is linear and independent of pixel position,
which can be represented by a polynomial function. By designing a plate having discrete markers with known
separate distance in between on the plate surface and projecting uneven fringe pattern onto it, one can calculate the
absolute phase of the centre on each marker. The 3D coordinates of all the markers can be obtained by a general
CCD camera calibration method. So coefficient set of the polynomial function are determined by using the obtained
absolute phase and depth of all the markers. The proposed method was applied to calibrate a phase-based 3D
imaging system. Experimental results and performance evaluation show that the proposed calibration method can
easily build up the accurate relationship between absolute phase and depth information data.

It is usually difficult to calibrate the 3-D vision inspection system that may be employed to measure the large-scale
engineering objects. One of the challenges is how to in-situ build-up a large and precise calibration target. In this paper,
we present a calibration target reconstruction strategy to solve such a problem. First, we choose one of the engineering
objects to be inspected as a calibration target, on which we paste coded marks on the object surface. Next, we locate and
decode marks to get homologous points. From multiple camera images, the fundamental matrix between adjacent images
can be estimated, and then the essential matrix can be derived with priori known camera intrinsic parameters and
decomposed to obtain camera extrinsic parameters. Finally, we are able to obtain the initial 3D coordinates with
binocular stereo vision reconstruction, and then optimize them with the bundle adjustment by considering the lens
distortions, leading to a high-precision calibration target. This reconstruction strategy has been applied to the inspection
of an industrial project, from which the proposed method is successfully validated.

Fringe Pattern Profilometry (FPP) is 3D surface measuring technique based on triangulation. The utilization of digital
projection in FPP system introduces significant phase distortion for Phase Shifting Profilometry (PSP), because of the
nonlinear response of digital video projectors, which is referred as gamma distortion. Considering that the distorted
phase has a stable function for a reference plane, this paper proposes an approach based on inverse function shift
estimation (IFSE) to detect the spatial shift of the distorted phase caused by object height. This spatial shift is
independent of projector's gamma distortion and accurate surface can be reconstructed based it. The simulation results
show that the proposed method can almost completely eliminate gamma distortion in reconstructed surface and we
obtain more than 5 times improvement in practical experiments.

A fast quality-guided flood-fill phase unwrapping algorithm is proposed for real-time 3D Fringe Pattern Profilometry
(FPP) system. The proposed approach consists of three steps. First, based on the phase maps acquired by phase shift
profilometry (PSP) techniques, a quality map is generated according to the phase variance adjacent pixels on the
wrapped phase map. According to the quality map, the phase map is divided into several parts which are categorised as
either rapid phase changing areas or smooth phase changing areas. Then quality-guided flood-fill phase unwrapping
algorithm is applied to rapid phase changing areas and non-guided path-following algorithm is used in the smooth phase
changing area. The proposed approach is much faster than the conventional non-guided path-following algorithm, and it
is more robust than the non-guided path-following algorithm. Experiments are carried out to verify the performance.

Structured light based 3D measurement is a typical optic method used to detect surface profile. The primary system projects
a structured pattern onto the measured surface. Through the phase shifting analysis, the depth profile is extracted with a
high resolution. In this paper a portable device bases on structured light method is introduced. The tool is used to inspect
edge breaks and corrosion depth on the turbine system parts. In order to maintain the inspection accuracy under the portable
operation, a simple but reliable calibration process and enhancement algorithms are needed to mitigate the variations of
user operations and system noise. In this paper, an effective calibration method with simple process is introduced to
calculate the system parameters and minimize the measurement errors. A set of image enhancement algorithm designed
specially for the structured patterns are introduced that is able to mitigate the noise clearly but won't decrease the
measurement resolution. The results are demonstrated through the calibration of a prototype system. Measurement results
are presented for sample surface using the filtering. The results show that the calibration process and image enhancement
works effectively to maintain a good accuracy and data quality.

Position and orientation estimation of the object, which can be widely applied in the fields as robot navigation, surgery,
electro-optic aiming system, etc, has an important value. The monocular vision positioning algorithm which is based on
the point characteristics is studied and new measurement method is proposed in this paper. First, calculate the
approximate coordinates of the five reference points which can be used as the initial value of iteration in the camera
coordinate system according to weakp3p; Second, get the exact coordinates of the reference points in the camera
coordinate system through iterative calculation with the constraints relationship of the reference points; Finally, get the
position and orientation of the object. So the measurement model of monocular vision is constructed. In order to verify
the accuracy of measurement model, a plane target using infrared LED as reference points is designed to finish the
verification of the measurement method and the corresponding image processing algorithm is studied. And then The
monocular vision experimental system is established. Experimental results show that the translational positioning
accuracy reaches ±0.05mm and rotary positioning accuracy reaches ±0.2o .

This paper presents a technique to choose appropriate light source for maximizing the contrast between the object and
the background surfaces in color vision application. From the physics of color image formation, three parameters which
affect generating signal of color digital camera are researched. An optimal color illumination for enhancing color
contrast can be found by maximizing these surfaces spectral reflectance. The discrimination of these surfaces spectral
reflectance was estimated by using average color difference in CIELab color space. A printed color patch which have
seven several colored characters was used to demonstrate the approach. For each colored character, appropriate Light
Emitting Diode (LED) illumination was selected to maximize the discriminability, which is more suitable than D65
illumination. These experiments illustrate the usefulness of properly chosen color illumination in color vision
application.

An anti-noise subpixel algorithm of phase-shifting of fundamental frequency was presented based on the phase-shifting
of Fourier transform and the anti-noise characteristics of low-frequency part of the phase spectrum of the image. The
essence of the algorithm is that the displacement caculation of the image is replaced by the movement caculation of the
coordinate, which makes the phase of the fundamental frequency zero under different coordninates when image position
changes. Under the circumstances that the image of the CCD autocollimator is polluted by the noises caused by
tempreture, the measuring accuracies of the normally-used barycenter, edge detection, Gaussian fitting algorithm and the
algorithm presented in this paper were compared. Experiment results show, the subpixel algorithm demonstrated here has
the advantages of strong anti-noise ability and high precision. The reliability of the algorithm is also disproved by the
peak location of the reconstructed image after the removal of higher harmonics. When applied to the one-dimensional
CCD photoelectric autocaollimator used in field conditions, fine linearity and ±3// measurement accuracy were
simutaneously obtained in the whole ±3600// measurement range when the temperature varies between -400C-600C.

In order to study the effect of structural parameters on the performance of fiber distance sensor with one normal single
mode fiber for illuminating and one inclined multimode fiber for receiving, a theoretical power-distance model is
established to describe the influence of the inclination fiber angle, the separation distance between the two fiber tips, the
offset distance between the two fiber tips and/or reflector angle on the modulation performance of the fiber distance
sensor. Numerical simulation results indicate that for the sensitivity of the sensor, it increases as the inclination fiber
angle increases, the separation distance decreases, the offset distance decreases and/or the reflector angle increases. For
the linear region, it increases as the separation distance increases, and/or the reflector angle decreases, however, it
change less obviously as the inclination fiber angle increases, and even remains unchanged as the offset distance is
changeable. For the dead zone, it decreases as the separation distance decreases, and/or the offset distance increases, and
the study would help the design of the inclined-fiber receiving distance sensor to the desired modulation performance.

Optical 3D Profile measurements have seen an increasing use in industry from electronics packaging to turbine engine
airfoils. This paper will review a number of industrial applications of optical 3D profilometry, what has been achieved,
and where new opportunities may be arising. Based upon the current applications, we will identify some of the key
barriers to successful implementation, and what is needed to address these barriers from an industrial perspective.
Finally, this paper will suggest some possible development areas that may greatly expand the application and
acceptance of 3D profilometry.

As an expensive natural stone, jade has a worldwide market. In the jade industry, the inspection and analysis basically
rely on the human eye and/or experience, which cause unavoidable waste and damage of these expensive materials.
Optical Coherence Tomography (OCT) is a fundamentally new type of optical sensing technology, which can perform
high resolution, cross-sectional sensing of the internal structure of materials. As jade is almost translucent to infra red
light, OCT becomes an ideal tool to change the traditional procedure to volume data based machine vision system. OCT
can also be used for anti-counterfeit of the expensive jade ware.

The fabric quality defect detection is very useful for improving the qualities of the products. It is also very important to
increase the reputation and the economic benefits of a company. However, there are some shortcomings in the traditional
manual detection methods, such as the low detection efficiency, the fatigue problem of the operator, and the detection
inaccuracy, etc. The existing 2D image processing methods are difficult to solve the interference which is caused by
non-defect case, just like the cloth folds, the flying thick silk floss, the noise from the background light and ambient
light, etc. In order to solve those problem, the BCCSL (Binocular Camera Color Structure Light) method and SFMS
(Shape from Multi Shading) method is proposed in this paper. The three-dimensional color coordinates of the fabric can
be quickly and highly-precision obtained, thus to judge the defects shape and location.
The BCCSL method and SFMS method can quickly obtain the three-dimensional coordinates' information of the fabric
defects. The BCCSL method collects the 3D skeleton's information of a fabric image through the binocular video
capture device and the color structured light projection device in real-time. And the details 3D coordinates of fabric
outside strip structural are obtained through the proposed method SFMS. The interference information, such as the cloth
fold, the flying thick silk floss, and the noise from the background light and ambient light can be excluded by using the
three-dimensional defect identification. What is more, according to the characteristics of 3D structure of the defect, the
fabric can be identified and classified. Further more, the possible problems from the production line can be summarized.

The geometric parameters of wheelsets, such as flange thickness, and rim width, and rim inside distance, are key
parameters that influence the wheel-rail contact. The online measurement techniques of these parameters are important to
ensure the safety of train vehicle and increase the reliability and efficiency of maintaining. The paper purposed the
measurement system based on the optoelectronic techniques. The measuring system is composed of the trigger sensor
and the laser displacement sensors fixed on the rails and the system can measure the wheelset's parameters when trains
pass through. The measuring results are improved by the wavelet analysis denoised. The average value difference is
between 0-0.3mm comparing the system and the manual that shows two methods are coincided. When trains pass
through the measuring system under the speed of 10km/h, measuring results shows that the system can meet with the
measuring requirement on line.

The steam flow in low-pressure turbine contained abundant water droplets, which will decrease the work efficiency and
pose potential threaten to operation safety, so measurement of steam wetness has brought great interest in electricity
generation industry. In this paper, a new measuring method using CCD (Charge Coupled Device) imaging technique was
proposed to determine the wetness in steam turbine based on the forward small angle light scattering theory. A simulated
steam turbine facility was designed to generate the wet steam, and light scattering experiments were carried out at
various working conditions in this device. The steam wetness parameters and droplet size distribution were obtained by
means of numerical inversion of the light intensity distribution based on Mie scattering theory. The results demonstrate
that the obtained data from the present analysis is in good agreement with the results of the theory analysis and previous
study, and the proposed method is proved to be suitable for steam wetness measuring and monitoring by further
development.

As an effect of globalization, product parts are manufactured more and more in different places. Due to the
manufacturing processes, (sub-) products are being transported back and forth and rearranged until they can finally reach
the consumer. Not only the environment is increasingly burdened, but also the natural resources are wasted increasingly
thoughtless. One reason is certainly because for decades the industry has had only an inflexible concept for the
inspection of (sub-) products, which cannot be easily adapted to changes in product layout, for example one robot with
one sensor or one rigid structure with a fixed number of sensors for one specific inspection task. This rigid approach is
unsuitable for the inspection of variant products. For these reasons, a new concept for 2D and 3D metric and logical
quality monitoring with a more accurate, flexible, economical and efficient inspection station has been developed and
tested in IOSB.

Computed Tomography (CT) testing is an important non-destructive testing technology in industry inspection. So the
important work of CT development is the value calibration and the precise result judgment. Bi-directional reflection
distribution function(BRDF) as the common spatial characteristic parameter can be fit for the CT data structure in theory
level and the CT data cube can be calibrated using BRDF in both spectral and spatial. Deferent processing calibrated
images can be achieved by calibrating CT data in deferent dynamic range using corresponding BRDF absolute value.
Thus the influence of BRDF calibration to CT data can be achieved from these serial calibration data and the optimized
arithmetic model for this calibration is established. Furthermore, the uncertainty of this value traceability and calibration
is analyzed and a corresponding example in CT industry NDT is given which illustrate that this calibration is useful in
analysis of PT image because it provide more true image and reduce the probability of error judgment.

In this paper, general theory of Fourier-transform spectrometer and polarization interferometer is presented. A new
design is proposed for Fourier-transform spectrometer based on polarization interferometer with Wollaston prisms and
linear CCD. Firstly, measured light is changed into linear polarization light by polarization plate. And then the light can
be split into ordinary and extraordinary lights by going through one Wollaston prism. At last, after going through another
Wollaston prism and analyzer, interfering fringes can be formed on linear CCD behind the analyzer. The linear CCD is
driven by CPLD to output amplitude of interfering fringes and synchronous signals of frames and pixels respectively.
DSP is used to collect interference pattern signals from CCD and the digital data of interfering fringes are processed by
using 2048-point-FFT. Finally, optical spectrum of measured light can be display on LCD connected to DSP with RS232.
The spectrometer will possess the features of firmness, portability and the ability of real-time analyzing. The work will
provide a convenient and significant foundation for application of more high accuracy of Fourier-transform spectrometer.

Signal to noise ratio is a fundamental performance of a image intensifier, which shows the photons
detection ability from object in low light level, and its determine detection range and image definition.
The input illuminated circular area must be 0.2mm in diameter on the photocathode, input illuminance
must be 1.02×10-4lx in signal to noise ratio value measurement of Image intensifier . So the paper study
a novel illuminance calibration method, which uses PMT photon counting detection technique. The
method can directly calibrate illuminance value of very low light sources in signal to noise ratio
measurement device of image intensifier. First, we introduce the principle of low light image intensifier
S/N tester. Secondly we research illuminance calibration method of 0.2mm in diameter on the
photocathode of image intensifier, design quasi-point low light luminometer, which adopts the photon
counting detection technique. So we research the radiation characteristic of standard light source with
2856K color temperature and calculate its output photon number, For high accuracy measurement on
quasi-point sources, vision function correction and cosine correction is made. Lastly, we research the
traceability diagram of this luminometer, which is traceable to our primary photometry metrology
standard device. The experimental results indicate the novel illuminance calibration method can
accurately directly measure illuminance of quasi-point sources. Comparing with the conventional
calibration method this novel method avoids the transfer error. The absolute illuminance calibration
uncertainty is analyzed. These analysis results are useful as a evaluating method for improving signal
to noise ratio of Image intensifier.

This paper is based on the triangulation method and the random digital speckles are projected on the reference plane and
the surface of the object, with the digital speckle correlation principle, solving the height of object and reconstructing
three-dimension of the object. Experimental results indicate that the digital speckle correlation technology in the
measurement of three-dimensional objects is validity, reliability.

Machine vision now is widely used as non-contact metrology which is a trend of measurement. In this article, a 3D
machine vision probe for engineering is designed. The XY axial measurement is done by 2D vision metrology, while the
Z axial height is measured by microscope through auto-focus (AF). As the critical part of probe, a long work distance
(WD) microscope is well designed. To attain the long WD, a positive and a negative lens group configure the microscope.
The microscope, with resolution of 1μm and WD of 35mm, is quite closed to diffraction limited as evidenced from MTF
(Modulation Transfer Function) chart.The AF, a key technology in probe designing, is particularly introduced. Images
acquired by microscope are calculated to get the AF curve data. To make the AF curve smooth, the images are denoised
and the curve is processed with a low pass filter (LPF). And a new method of curve fitting is involved to get the accuracy
focused position.The measurement with probe shows that the uncertainty is 0.03μm at XY axial plane, while the
uncertainty is less than 3μm at Z axial height. It indicates that our probe achieves requirements.

Principle of using infrared dual-frequency He-Ne laser as a displacement sensor is presented. By inserting birefringent
elements into laser cavity, one laser beam is splitted into two orthogonally polarized laser beams. When cavity length is
changing, two beams appear one after another. Power turning curves are formed, which provide a method of
displacement measurement. Compared to red He-Ne laser, infrared He-Ne laser has the feature of higher gain and
corresponding stability. By counting numbers of equal-intensity points and combining subdivision techniques,
displacement sensor based on infrared dual-frequency He-Ne laser is expected to afford measurement range of 100mm
with resolution of 10 nm.

Finding the position and orientation between a camera and a target with respect to a scene object from n correspondence
points is crucial for many computer and robot vision tasks. With a limited number of correspondence points, the
closed-from solution is applied to solve the pose estimation problem. To estimate the pose between the camera and the
target from the four reference point, a pose estimate model is built with the four projection line between the 3D space
point and 2D image point, under the full perspective projection of the camera. The transformation matrix is determined
by the coordinates of four reference points in camera coordinate system and the target coordinate system respectively.
To figure out the transformation matrix, the distance factor of the four reference points in camera system must be
calculated. Considering the quality of the triangle, the pose estimate model with is simplified, which avoid the iteration,
as while as taking the advantage of the data redundancy. Considering the specific relationship of the four reference
points, the Levenberg-Marquardt algorithm is used to figure out the unknown parameters in the pose estimate model.
Then the position and orientation between the camera and the target is obtained with respect to the coordinate
transformation matrix from the camera coordinates to the target coordinates. In the experiment, both synthetic and real
data are used to examine the accuracy and stability of the pose estimate algorithms with four points. Experiment result
shows the distance measurement precision better than 0.03mm, and the angle measurement precision better than 0.2°.

An experiment measuring system is introduced. Angle-resolved single-band and multispectral bidirectional
reflectance distribution function measurements are operated in ultraviolet band. Hemisphere spectral reflectivity of some
samples is measured. An optimizing modeling method, particle swarm optimization (PSO) is used to model the laser
BRDF data of typical samples. The results are fitted with the models developed above using optimize algorithm to get
the parameters. Spectral BRDF of samples calculated with the model are in good agreement with the measured data. And
these studies about measuring and optimizing modeling of typical roughness target samples in ultraviolet band have
significant meanings in a lot of related fields.

A photoelectric autocollimator, which consists of an optical autocollimator and an area CCD and whose standard
deviation is less than 0.5" calibrated by a dual-frequency laser interferometer HP5528A, is proposed in the paper. The
positional precision of a NC motorized stage is detected automatically and quickly by applying the photoelectric
autocollimator calibrated and an optical polyhedron to finish the error compensation of the stage. According to GB/T
17421.2-2000, when the polyhedron and the stage both revolve with the same axis, the positional error of the stage is
measured by the photoelectric autocollimator and then sent back to the controlling system of the stage manually or
automatically. Experimental results show that an angle can be measured by the photoelectric autocollimator and the
calculated position accuracy agrees with that which is measured by a Triangle autocollimator 500-57 at the same time.

A new method based on confocal microscopy is presented to measure the distance between the focus of an objective lens
and the curved surface. The focus error signal based on this method is constructed. And this signal features not only the
possession of the linear relationship to the defocus, that is the distance between the focus of the objective lens and the
curved surface, and direction information of defocus and a wide measuring range, but also the independence of the tilt
angle of curved surface, the power fluctuation and the like.

Raman spectroscopy is often hampered by strong fluorescence background that can easily bury the much weaker Raman
signal. One of the most widely used techniques to reject the fluorescence disturbance is the shifted-excitation Raman
difference spectroscopy (SERDS), which incorporates multiple wavelengths as excitation sources. This paper proposed a
SERDS system with 532 nm and 526.5 nm DPSS lasers and a home-made holographic notch filter. In this system, two
lasers illuminate the sample alternatively, and two series of spectra are acquired to generate the difference spectrum. And
then a regularization constrained least square algorithm is proposed to reconstruct the conventional Raman spectrum
from the difference spectrum. Computer simulation of this algorithm is provided and the preliminary experimental
results are presented. It demonstrates that this system can effectively reject the fluorescence.

When applying phase-stepping interferometry to measure wavefront with aberration, distortion is
caused by various factors and the main one is phase-shifting error from phase shifter. In this paper,
the calculation theory and consequence in measurement error of the phase shift algorithm are
discussed. These algorithms include traditional three-phase algorithm, traditional four-phase
algorithm, traditional five-phase algorithm, carre algorithm, new compensating four-phase
algorithm and new compensating five-phase algorithm. According to the theory analysis and
computer stimulation, these methods are compared through introduce phase-shifting error,
wavefront aberration and Gauss noise, the results show the new compensating five-phase
algorithm is immune to phase-shifting error, and its result is insensitive to Gauss noise, it can
improve measurement accuracy effectively.

Blob detection which focuses on detecting points or regions of a different intensity than the surrounding image is
increasingly used in consumer products such as human-computer interfaces and motion tracking. Because blob detection is
computationally intensive but requires relatively simple arithmetic operations, it is an ideal candidate for parallelization in
hardware. The main goal of this paper is to develop a hardware implementation for blob detection structure that is able to
detect multipoint in a video image on a Xilinx FPGA platform. This system consists of three functional blocks. The first
block use a dual port memory to get the histogram of video data and then to obtain the threshold value for the image frame.
The second block applies the threshold value to the video stream data, gets the line connected component, and these
components are then transferred into the third block by Fast Simplex Link (FSL). The third block is a Microblaze processor
which does the label connection and gets the center of points. This approach is implemented on a Xilinx Spartan3 chip with
640 by 480 resolutions up to 30Hz. It can be used in various low cost consumer applications.

Two on-line inspection methods of printed matter based on optical image subtraction are proposed, using two kinds of
spatial light modulation (SLM) respectively, which are TFT-LCD and CRT-LCLV. The test image of printed matter is
obtained by CCD, while the standard image of printed matter is saved in computer. The test image and standard image
are jointly displayed on SLM by computer as the input image of an optical image subtraction system, which is an optical
4f system with a sine-grating between two lenses. The subtraction image will occur at the output plane, which contain all
defects of the test image. Comparing to machine vision method, this inspection method of printed matter based on
optical image subtraction is advantaged because the inspection process is accomplished by the optical system, avoiding
any complicated arithmetic. The precision of printed matter inspection is defined by the frequency of SLM and the
sine-grating. The relationship between parameters of the subtraction image and parameters of optical system is analyzed.